Speaker
Description
Materials that undergo controllable structural and property changes upon external stimuli are known as stimuli-responsive or “smart” materials. Understanding the transitional pathway and the out-of-equilibrium state of their micro-structures are crucial for the establishment of a dynamic structure-property relationship. With increasing neutron flux, time-resolved small angle neutron scattering experiment allows for capturing of the transient structures down to seconds. Higher time resolution can be achieved through repeated measurements. However, it is cumbersome to synchronize additional stimulating sources into an operational TOF instrument, especially when precise timing repeatability is required.
Traditionally, data acquisition is hardware synchronized with the external sample environ-ment or vice versa [1, 2], which requires modification or replacement hardware and software components. Instead, we propose an alternative approach that is able to decouple the trig-gering of the external device from the data acquisition process. A mini mechanical shutter made of neutron absorption material is integrated in the sample environment equipment control system and mounted in front of the sample holder. As part of the external device, the status of the mini shutter (sample’s exposure to neutron) can be easily synchronized with the initiation of the external stimulation, while the data acquisition process can be initiated at any time earlier. From the acquired time-of-flight neutron data, the sudden increase in neutron counts serves as the indication of the initiation of the external stimulation, making the allocation of the initiation point of the transition process straightforward. The initiation time accuracy of the SANS experiment is thus optimized to the response time of the mechanical shutter (~ms). The successful implementation of this new experimental platform will provide a feasible means to study the physical and chemical processes involving rapid microstructure transitions in the field of soft matter.
References
[1] D.S. Li, Y.T. Lee, Y.Y. Xi, I. Pelivanov, M. O'Donnell, L.D. Pozzo, A small-angle scattering environment for in situ ultrasound studies, Soft Matter, 14 (2018) 5283-5293.
[2] S. Schmolzer, D. Grabner, M. Gradzielski, T. Narayanan, Millisecond-range time-resolved small-angle x-ray scattering studies of micellar transformations, Phys Rev Lett, 88 (2002) 258301.
